The invention concerns a sinker for a knitting machine that operates especially according to the relative technique, comprising a front, a back, a head arranged on one end and having a sinker throat and a knock-over edge, a control butt designed to make possible movements in a longitudinal direction and protruding from the front, and at least one rocking element designed to make possible pivot movements transverse to the longitudinal direction and provided on the front side. The invention also concerns a knitting machine equipped with such a sinker.
In a knitting machine operating according to the relative technique, the knock-over and holding-down sinkers are pushed, during a drawing-down movement of the knitting needles occurring after thread take-up, in a direction opposite to his movement. The needle stroke required to form a stitch is then smaller than during use of the normal knitting technique, which permits the use of less steep raising and take-off cam pars for the needles and sinkers and thus an increase in knitting speed.
Known knitting machines operating according to the relative technique of the generic type just mentioned are generally designed as circular knitting machines (DE 33 11 361 C2, DE 33 48 030 C2, DE 33 30 530 C1) and are mostly provided with sinkers designed as two-arm levers. These are pivotally mounted by means of central bearing sites on the bottoms of grooves formed in a needle cylinder or the like and can be displaced in their longitudinal direction. Their pivot movements are produced by means of swivelling cam parts that act on rocking elements provided on the front sides of the sinkers and frequently designed in the fashion of butts. These movements occur, in the case of a circular knitting machine, in a radial direction relative to the needle cylinder axis.
A problem that occurs during operation of such circular knitting machines consists of the fact that the swivelling cam parts, because of unavoidable tolerances during manufacture, must be adjusted relative to each other so that the sinkers are arranged with a certain play, i.e., are mounted to pivot transverslye to the longitudinal direction by the amount of this play. For this purpose, during adjustment of the machine for instance, one (the upper) swivelling cam part is adjusted so that it fixes the position of the sinkers in a position pivoted maximally toward the needle cylinder. The other (lower) swivelling cam part is then adjusted so that it fixes the positions of the sinkers in a position pivoted maximally away from the needle cylinder with a chosen play of, say, 0.2 to 0.5 mm. Because of this, on the one hand, additional working steps are required during setup of the machine and, on the other hand, the mentioned play results in unsteady running of the sinkers and thus undesired clattering noises during operation.
Knitting machines operating according to the relative technique and sinkers of the generic type just mentioned are also known, in which the knock-over and holding-down sinkers are biased by an elastic spring force in the direction toward an end position of their transverse movement. The spring force is applied by means of an endless annular or tension spring, enclosing the needle cylinder of a circular knitting machine and acting on the front sides of the sinkers. Since this spring biases the corresponding lever arms of the sinkers in the direction of the corresponding sinker carrier, either sinkers in the form of two-arm levers must be provided even if only one active swivelling cam part is present (DE 32 46 512 C2), or the swivelling cam part must be formed on the sinker carrier (DE 31 08 041 C2). This type of spring must also be suitable to act on all sinkers present, for which reason its spring force must be very large. Above all, however, the problem arises that the sinkers easily enter between two adjacent turns of the spring and are then jammed instead of being biased by the spring. Both variants lead to arrangements that are not satisfactory in a design respect, unfavorably influence the design height of the cam arrangements, and are prone to breakdown.
Corresponding problems can develop in knitting machines, in which the sinkers are supposed to be pivotable back and forth for reasons other than those just mentioned.
One object of this invention is, therefore, to design a sinker of the kind specified above so that if mounted in a knitting machine, an adjustment of a defined bearing clearance for the sinker is not required.
A further object of this invention is to design the sinker such that an adjustment of a defined bearing clearance for the sinker is not required even if unavoidable and other manufacturing tolerances occur.
Yet another object of this invention is the design of a sinker having, in dependance on its configuration, a favorable design height.
A further object underlying this invention is to provide a knitting machine with sinkers of the kind specified above such that an adjustment of a defined bearing clearance of the sinkers with respect to the cam arrangement of the knitting machine is not required.
And yet another object of the invention is to design the sinkers of a knitting machine operating according to the relative technique in such a manner that no undesired vibration and noise development occurs during operation of the knitting machine.
These and other objects are solved in accordance with this invention by means of a sinker of the kind specified above which is characterized by the fact that it has a spring element acting transversely to the longitudinal direction.
A knitting machine according to one embodiment of this invention is characterized by sinkers each either having a rocking element being arranged between said head and a bearing site intended for being supported on a carrier and provided on the back, wherein said spring element has a support site arranged between said head and said pivot site or having a bearing site being intended for support on a carrier, provided on the back and arranged between the head and said rocking element, wherein said spring element has a support site for being supported on a carrier of the machine, said support site lying on a side of said rocking element facing away froom said bearing site.
A knitting machine according to a further embodiment of the invention is characterized by by sinkers being provided with two rocking elements arranged on the front and spaced in the longitudinal direction, wherein the spring element has a support site for being supported on a carrier of the machine and being arranged in the longitudinal direction between the two rocking elements.
A knitting machine according to another embodiment of the invention is characterized by sinkers being provided with two rocking elements spaced in the longitudinal direction and arranged on the front, wherein a bearing site is situated in the longitudinal direction between said rocking elements, but on the back.
The invention provides the advantage that the sinkers themselves are set up to compensate for the manufacturing tolerances. For this reason, regardless of their design selected in the individual case, both tension springs and swiveling cam parts situated in the sinker carrier can be avoided and proven knitting machine designs can be retained.
The invention is further explained below in conjunction with the accompanying drawings by means of practical examples. In the drawings: